Project Summary Population-level approaches for obesity prevention that leverage behavioral science have potential for large reach and sustainability. Behaviorally-informed interventions such as traffic light nutrition labels, choice architecture (product placement), social norms (peer comparison) feedback, and financial incentives improve healthy food choices in cafeteria settings. Although these interventions change behavior in the short-term, it is not known whether they can induce long-term behavior changes and improve health. It is also unknown whether psychological traits, cognitive skills, and genes moderate the effects of these interventions on behavior and health. The long-term goal is to identify low-cost, targeted, and scalable behavioral interventions to increase healthy food choices and prevent obesity. The overall objective of this project is to examine the psychological traits, cognitive skills, and genes that may influence the impact of a behaviorally-informed intervention on dietary choices, weight, and other objective health indicators. To achieve this objective, the research team is conducting a randomized controlled trial to test an innovative behavioral intervention to prevent weight gain and reduce cardiometabolic risk factors over two years in 600 hospital employees who visit the worksite cafeterias ( ). This intervention targets intentions, knowledge, skills, and the R01 HL125486 environment to encourage healthier food choices. At the hospital worksite, all cafeterias use traffic- light nutrition labels (green=healthy, yellow=less healthy, red=unhealthy). A one-year intervention, designed to increase employees' awareness and use of the traffic lights, includes: 1) personalized, automated messaging about food purchases and health behaviors; 2) social norms comparisons; and 3) financial incentives. Outcomes measured at baseline and one and two-year follow ups include: weight/BMI, blood pressure, lipids, hemoglobin A1c; cafeteria purchases; and 24-hour dietary recalls. The proposed research will significantly expand on this work by examining psychological traits (impulsivity, self-control, social acceptance), cognitive skills (numeracy, health literacy), and genes (97 known BMI loci) that are associated with obesity and poor health and are specifically targeted by the intervention. We will use validated measures to assess traits and skills and well-established methods for genotyping and calculating genetic risk scores. Aim 1 will determine if psychological traits moderate the behavioral intervention effects on diet and weight. Aim 2 will determine if cognitive skills moderate the behavioral intervention effects on diet and weight. Aim 3 will determine if genetic risk for obesity moderates the intervention effect on weight. In secondary analyses, potential mediators of diet and weight outcomes, including dietary intent, self-efficacy, reward sensitivity, perceived norms, and perceived stress, will be assessed. Implications: Results of this research will l will inform the future design and implementation of more effective, tailored, and sustainable population approaches for obesity prevention.